This invention relates to circuit breakers and particularly to ambient compensated remotely resettable circuit breakers.
The typical circuit breaker has characteristics that become significant drawbacks under certain operating conditions. For example, if a bimetallic element is part of the breaker, the use of the breaker in environments where extreme temperature conditions exist is handicapped by the effect the temperature has on the operating characteristics of the bimetallic element. Certain ambient compensated circuit breakers have been devised to overcome this handicap. For example, U.S. Pat. No. 4,032,876 of Lyndon W. Burch shows a circuit breaker having a monometallic element with fixed divering legs. Load current flows through one of the legs. When the current reaches overload magnitude, the thermal expansion of the leg causes it to bend and unlatch a biased element to break circuit continuity.
The resetting of circuit breakers can present other problems. Often it is desirable to reset the circuit breaker from a remote location. If space and weight are significant factors, the resetting technique must be carefully chosen. In particular situations, for example, an electromechanical solenoid reset arrangement would be unsatisfactory because of the size of the solenoid. Also the large current necessary to operate a solenoid requires heavy conductors to power the solenoid. A typical environment in which all the foregoing adverse factors are present is the airplane, in which temperature extremes occur routinely, and in which space and weight considerations are vital.
Accordingly, it is an object of this invention to provide a circuit breaker that is substantially independent of ambient temperature and that is remotely resettable with minimal current. Other objects of the invention are to provide a circuit breaker that is reliable, inexpensive to produce, and lightweight.